A major concern for immobile patients and like persons are medical conditions that form clots in the blood, such as, deep vein thrombosis (DVT) and peripheral edema. Such patients and persons include those undergoing surgery, anesthesia, extended periods of bed rest, etc. These blood clotting conditions generally occur in the deep veins of the lower extremities and/or pelvis. These veins, such as the iliac, femoral, popiteal and tibial return deoxygenated blood to the heart. For example, when blood circulation in these veins is retarded due to illness, injury or inactivity, there is a tendency for blood to accumulate or pool. A static pool of blood may lead to the formation of a blood clot. A major risk associated with this condition is interference with cardiovascular circulation. Most seriously, a fragment of the blood clot can break loose and migrate. A pulmonary emboli can form from the fragment potentially blocking a main pulmonary artery, which may be life threatening. The current invention can also be applied to the treatment of lymphedema.
The conditions and resulting risks associated with patient immobility may be controlled or alleviated by applying intermittent pressure to a patient's limb, such as, for example, a leg to assist in blood circulation. For example, sequential compression devices have been used, such as the device disclosed in U.S. Pat. No. 4,091,864 to Hasty. Sequential compression devices are typically constructed of two sheets of material secured together at the seams to define one or more fluid impervious bladders, which are connected to a source of pressure for applying sequential pressure around a patient's body parts for improving blood return to the heart. The inflatable sections are covered with a laminate to improve durability and protect against puncture. As part of the compression device, the two sheets are structurally designed to withstand a changing pressure over time under repeated use.
The impermeability of the sleeve makes it uncomfortable for the patient because moisture (i.e. perspiration) is trapped between the impermeable sheet and the patient's body part. This leads to the patient's unwillingness to wear the sleeve, thereby, endangering the health of the patient. Moreover, the sleeve is generally non-stretchable and bulky because the bladders must be able to retain a significant amount of fluid pressure during treatment. Thus, the prior art sleeves restrict the mobility of the patient. Also chafing of a patient's limb can occur because the prior art designs retain the inflatable bladders in a fixed position when under pressure. As the pressure changes during treatment, the bladders press and release against the patient's limb, rubbing and chafing the skin. A bladder may wrinkle or fold which can cause further irritation during a compression cycle. The final construction of a prior art sleeve is bulky, rigid and may feel heavy to a person over an extended period of use. The present invention is directed to solving the above mentioned deficiencies without compromising durability and clinical effectiveness.
As stated above, prior art devices are constructed for durability and strength. As shown in U.S. Patent Publication No. 2005/0187503 A1 to Tordella, Tordella describes a sleeve with a top and bottom sheet. The sheets are fixed at the perimeter to form an inflatable section or bladder, as shown in FIG. 2. The material forming the chambers or bladders is polyvinyl chloride or polyethylene. These materials are impervious to moisture as they need to be fluid tight and thick enough to withstand thousands of compression cycles without bursting. Tordella provides some cooling when the device provides for vent holes placed about the sleeve. Also, a slit is introduced through the sheets, but Tordella's slit is not within the area defined by the chambers (i.e. bladders). Generally, access to skin will provide evaporation of bodily fluids collected at the openings, but the Tordella invention does not provide for removing fluid trapped beneath the impervious sheet away from the openings. The evaporation is limited to the openings and the immediate area under the impervious sheet near the opening. At least some of the embodiments of the present invention provide a solution to the problem of trapped fluid by moving the fluid from underneath the impervious sheet, at a sufficient rate, to a plurality of openings positioned, sized and shaped to maintain blood flow and evaporate the moisture as described below. The Tordella sleeve construction is similar to the Model 9529 SCD Express device (knee length sleeve) available in the United States from Tyco Healthcare Group L.P., which is discussed in more detail below.
There are other prior art attempts to improve comfort through breathability and evaporation. U.S. Pat. No. 3,824,492 to Nicholas is directed to a garment that provides pulsating pressure to a lower extremity. A number of holes are placed at the toe area. Air entering the holes is pulled across the patient's skin through an air space provided by the device when worn. Nicholas has a hard outer shell. The Nicholas device suffers from a number of drawbacks not found in the present invention. The compression sleeves of at least some embodiments of the present invention are elastic, at the inner layer and outer layer, to improve patient mobility and flexure. Instead of a hard outer shell like Nicholas, the present invention has in some embodiments a breathable, soft and elastic outer covering. The elastic outer cover of the present invention helps the sleeve conform to the limb under pressure. The present invention does not have the structure for a channel at the skin to move air across the skin and into the ambient environment.
Hasty (U.S. Pat. No. 4,091,804) and Annis (U.S. Pat. No. 4,207,876) disclose a plurality of openings in communication with a ventilation channel. Air is forced through the channel and openings onto the skin by a compressor. The present invention does not use a ventilation channel within the layers of the sleeve. Furthermore in preferred embodiments of the present invention, the compression sleeve does not use its compressor to force the air through the openings onto the skin though the channel. In embodiments of the present invention, air at the openings interfaces with the wicking material to evaporate wicked moisture as described more fully below. The transport mechanism can be the wicking material in present invention. Other devices such as Jacobs (U.S. Pat. No. 5,489,259), provide for direct access to a portion of the patient's limb, but the Jacobs' device suffers in that cooling (evaporation) is limited to the localized openings. The Neal reference (U.S. Pat. No. 5,693,453), describes openings of various geometries, but the size, shape and distribution is a matter of convenience of use. The Neal device is not directed to prophylaxis treatment.
Breathability is associated with cooling through evaporation, as air must be allowed to pass over the openings to the skin. Faster evaporation can occur if a device can breathe through its outer layer which is a problem not solved in the cited references. A number of cited references mention breathing to avoid sweat build-up, but none of the references are directed to providing prophylaxis treatment using sequential compression. A device to Hall (U.S. Pat. No. 6,520,926), describes a support socking that is breathable, but Hall provides no additional detail on how it is made breathable. A device to Roth (U.S. Pat. No. 7,044,924), describes that various sized holes may be punched through both the inner and outer sheet 202/204, between adjacent seams 234 or 242 to allow for ventilation. Further, a moisture-wicking lining material may be applied to the surface of the inner sheet 204 for comfort. The lateral seams 230, 232 and 234 and the longitudinal seams 238 and 240 form a plurality of inflatable bladders 250. The Applicants adapt their inner sheet to provide wicking properties because the Applicants discovered laminating or applying the wicking material to a sheet may compromise the wicking ability of material. The fibers of the wicking material would be interrupted, made discontinuous by the lamination; therefore, interfering with the capillary action of the wicking fibers as described below.
Roth may introduce a low pressure area adjacent to bladders which has been shown to promote blood pooling. The Applicants particularly structured at least some embodiment of their device to avoid blood pooling by configuring adjacent bladders to minimize low pressure areas between the adjacent bladders. Applicant's device was demonstrated to maintain clinical efficacy as described below. Roth does not provide any information regarding the clinical efficacy of its device and does not provide any figures showing its openings or its wicking material. A sock device to Linnane (U.S. Patent Publication No. 2006/0010574), describes a compression stocking with a wicking material near the person's skin for wicking moisture along channels to the outside of the stocking. The present invention directs moisture to a plurality of openings sized, shaped, and located along the compression device for maximizing evaporation while maintaining clinical efficacy.
Elasticity is found in the prior art and is commonly understood to be an important benefit for compression stockings such as the T.E.D®, sold by the assignee of the present invention. A drawback of the prior art sequential compression devices, like that shown in Hasty, is that the bladder material is flexible but not elastic. The prior art bladders are formed as part of a laminated construction adding further rigidity and durability. The Tordella reference discloses a sleeve with flexible, elastic sections between the inflatable sections or portions to facilitate mobility of a patient. Tordella does not disclose an elastic design circumferentially and longitudinally along the sleeves entire length, which is solved by the present invention.
The present invention helps overcome patient discomfort without decreasing clinical effectiveness, as shown in supporting lab tests disclosed in this application. An important objective is to improve patient compliance, defined as using the sleeve as prescribed by a doctor. There is a direct correlation of patient compliance with patient comfort. Compliance with mechanical compression devices has always been a concern in healthcare. A clinical staff is overworked with patient loads and duties and thus one-on-one patient care time is at a premium. Often it has been reported that patients, will become uncomfortable wearing compression sleeves and request that the sleeves be taken off, even though they may be necessary to prevent a fatal occurrence of a pulmonary embolism. Clinical staff may not have time to fully educate the patient on the importance of wearing the sleeve, and may not have the time to ensure that the patient is constantly wearing the sleeve. For example, a research study performed by the CMAJ Clinical Practice Guidelines for the Care and Treatment of Breast Cancer, discussed treating lymphedema associated with breast cancer. The study indicates patients are not compliant because the devices are generally difficult to use and not comfortable. It is this reason that compression sleeve manufacturers are trying to introduce more comfortable sleeves while maintaining the clinical efficacy already found in the prior art devices. With the need for shorter stays at the hospital and more outpatient surgery, the need for more a comfortable device that is easier to use, while maintaining clinical efficacy, is a long-felt need in the industry.
As stated above there is a long felt need, not found in prior art sleeves for improving comfort without compromising clinical effectiveness. Other prior art devices on the market, such as Aircast®, Huntleigh®, and Hill-Rom® suffer from a number of drawbacks, disclosed below, and solved in the present invention. Preferred embodiments of the present invention provide substantial cooling without compromising the clinical efficacy of the prior art devices such as Kendall's Model 9529 and 9530 compression sleeves in providing prophylaxis DVT. The present invention is directed to improving patient comfort and thus compliance in terms of physician prescribed use. The following list of features is included in the construction of at least some embodiments of the present invention: soft, cool, easy to use and apply, non-irritating, flexible, fit a patients changing needs, and improved patient compliance.
The present invention in its preferred embodiments is engineered to provide the maximum amount of evaporation, which is a function of wicking properties and opening size, location and shape, while minimizing any negative impact on blood flow augmentation or clinical efficacy. Blood flow is dependent on opening size, shape and location, that is, the opening properties must be minimized not to interfere with blood flow, while maximizing the evaporation of trapped moisture beneath the impervious layer.
As is known in the art, a compression sleeve is used to provide prophylaxis treatment to a wearer's body part. This treatment is to help prevent the formation of blood clots by increasing the velocity of blood, in a cascading manner along a limb toward the heart. The illustrated and described embodiments of the present invention wrap around the full circumference around a patient's limb. The embodiments of the present invention are not limited to full wrap devices. The structural changes that accomplish the features described below will enhance the comfort and use of the prior art devices, but not necessarily at the expense of their claimed clinical efficacy.